Photocatalytic degradation of the herbicides propanil and molinate over aqueous TiO_2 suspensions: identification of intermediates and the reaction pathway

摘要

The light-induced degradation of propanil and molinate under simulatd solar irradiation has been investigated in aqueous solutions containing TiO_2 suspensions as photocatalysts.The study focus on the identification of possible intermediate products and the determination of inorganic ions formed during the process, using several powerful analytical techniques such as gas chromatography-mass spectrometry (GC-MS) and ion chromatography (IC). The primary degradation of propanil and molinate has been a fast process with half-lives varied from 4.3 to 2.9 min, respectively, and following pseudo-first-orderkientcs according to the Langmuir-Hinshelwood model.The stoichiometric transformation of organic chlorine into chloride ion and organic sulfur to slfate ions was observed fro propanil and molinate, respectively , whereas oxidation of nitorgen to nitrate ions took